The cameo shown in the photograph is a transferware cameo. It is made of pottery which has a design transferred onto it. After the design of the cameo is put onto the pottery disk, hand-painted details are sometimes added. The pearls, the flowers in the hair and the folds in the fabric are painted by hand on top.
This method of putting designs onto jewelry via transfer allows for mass production. Because it is mass-produced, a pin like this will most likely never have the value that a fine hand-carved cameo will have. Regardless, it is pretty. This pin, which is stamped LIMOGES on the back, is from the 1950s-1960s.